1. Field of the Invention
The present invention relates to a novel construction of driven roller tracks and to the components thereof.
2. Description of the Related Art
Thanks to many variants, roller tracks are the ideal way of transporting various goods.
Among others, roller conveyors are also used to connect belt conveyors on a straight section or in curves. This often requires buffers capable of compensating for different clock cycles of machines. Here, accumulating conveyors with which an accumulating function can be obtained are sometimes used, which makes sense particularly for interlinking of machines.
Among others, roller tracks can be used as light roller tracks or as standard roller conveyors.
Light roller tracks, which are also referred to as minute roller conveyors, serve to transport small, light goods to be conveyed, in particular over short distances. Generally, light roller tracks transport general cargo of at most 15 kg per meter at a conveyor speed of approximately 1 m/s. For example, a light roller conveyor having a length of 2 meters may be comprised of 57 rollers, each having a diameter of 30 mm (30 mm roller) and a roller pitch of 35 mm, so that also small goods can be transported securely without getting caught in the roller track.
Standard roller conveyors have rollers with a 50 mm diameter (50 mm roller) and a roller pitch of approximately 75 mm and more. The rollers are made of plastics or metal. Roller conveyors are stationary units in conveying engineering, which move general cargo over an assembly of rollers.
There are different drive concepts for driven roller tracks.
In the case of straight conveyors, chains are used at higher driving torque and lower speeds, whereas poly-V belts are used at medium torque and round-section belts at lower torque. Sometimes, flat belts are used as well. The arrangement of the belt may be in a tangential manner to the driven rollers or in a wrapping manner to the driven rollers. In the latter case, a drive may be accomplished from roller to roller or by means of a driveshaft.
With a tangential drive, the belt contacts the roller tangentially. Here, the belt is supported either by support rollers or by means of a slide rail, so that the required normal force between the conveyor roller and the belt is achieved. Depending on the belt used and the torque to be transmitted, a more or less strong pretension of the belt is required.
In particular in the case of the tangential drive, the belts have to be shortened to the required length and welded together on the spot, or additional idler pulleys and complex tensioning devices have to be used if prefabricated drive belts of a predetermined length are to be used. It has to be taken into account that only a few conveying means can be shortened to the desired length anyway and that the welding quality is difficult to ensure on the spot.
For a targeted effect, the transmission element always has to be tensioned strongly and be retensioned regularly. Too low a tension can lead to strong strand vibrations or to a skipping of the teeth on the tooth lock washer. Too high forces cause a strong load on the bearings and the belt, and influence the gear components negatively by signs of wear. Moreover, high forces, a strong rigidity of the belt, a plurality of belt redirections and/or the use of slide rails lead to a strong friction loss, to wear, and to an unnecessary energy loss.
In the case of a roller-to-roller drive, one roller connected to a drive motor drives the subsequent roller by means of a transmission element in a usually nonpositive manner. A further transmission element can drive the next subsequent roller, etc. Here, the transmission elements wrap around half of the roller each.
For a large number of rollers, many transmission elements are required, so that friction and thus energy consumption and wear increase. For a roller conveyor having a length of 2 m and rollers of 30 mm, approximately 60 belts are required. The speed loss has a negative effect here as well, since due to the slip during each transmission from belt to roller the last roller may exhibit a clearly different rotational speed than the first driven roller. In order to avoid these disadvantages, motorized rollers are used to some extent. These motorized rollers are integrated across the roller track section, so that one motorized roller, via round-section belts, drives e.g. four rollers in front of and after the motorized roller in a continuous manner.
A drive by means of a driveshaft also requires many wraps of the transmission element, which leads to corresponding friction losses. Moreover, the assembly of the transmission element is complex.
Therefore, for driven roller tracks, in particular for light roller tracks in which all or at least a major part of the rollers are/is to be driven, there is the problem that a plurality of driven rollers, having their own drive unit, can only be realized in a complex and expensive manner. Driven roller tracks, in which a plurality of rollers is driven via a drive unit, require a comparatively strong drive unit, since the power transmission from the drive unit involves friction and thus entails high energy consumption. In addition, a friction-involving operation often leads to wear and to a premature failure of components of the roller track.
The above problems occur both with straight conveyors and with curved conveyors, curved conveyors being more likely problematic, since a drive along a curve requires a corresponding redirection of the transmission element or transmission elements, which can lead to more friction loss and wear.
It therefore is the object of the invention to provide an easy-to-assemble roller conveyor, which is easy to mount, versatile in use, reliable, and consumes little energy during operation.